The present invention concerns a turntable of a rotary crane of the king post type having a pylon anchored to a base plate, platform, or similar base, with a support frame mounted on bearings above and suspended from the pylon, coupling devices connected to the support frame to permit the coupling of a crane boom, and support devices to allow the support frame to revolve on the longitudinal axis of the pylon, the support devices having an upper support for the suspension of the support frame on an upper end section of the pylon and a lower support for the suspension of the support frame on a lower section of the pylon, and the lower support has a bearing journal that surrounds the pylon.
Rotary cranes of the king post type are known, for example, from U.S. Pat. No. 5,328,040 or U.S. Pat. No. 5,310,067. The turntable of such cranes is mounted on a bell-like mounting on, and is mounted to revolve around, the upper end of the pylon by means of a radial and an axial support and at its lower end by means of an axial support, so that the entire turntable can be revolved on the longitudinal axis of the pylon. Rotary cranes of this type are used especially as offshore cranes on oil rigs, ships and the like. In rotary cranes of this type, erection is particularly problematic, especially because of their size but also because of the harsh environment, such as high seas, strong winds, and similar conditions. Because of the radial support, it is difficult to position the turntable above the pylon. The turntable of the rotary crane according to U.S. Pat. No. 5,328,040 or U.S. Pat. No. 5,310,067 must be raised above the pylon, which is quite high, and must be lined up axially and positioned on the pylon from above, a time-consuming and difficult procedure.
The problem to be solved by the present invention is to create an improved rotary crane that avoids the disadvantages of and constitutes an advantageous further development of the stat e of the art. Especially, the turntable of the crane is to be improved in such manner as to permit easier assembly of the crane.
According to the invention, this problem is solved by means of a turntable of a rotary crane of the king post type having a pylon anchored to a base plate, platform, or similar base, with a support frame that can be slid above and suspended from the pylon, coupling devices connected to the support frame to permit the coupling of a crane boom, and support devices to allow the support the support frame to revolve on the longitudinal axis of the pylon, the support devices having an upper support for the suspension of the support frame on an upper end section of the pylon and a lower support for the suspension of the support frame on a lower section of the pylon, with the lower support having a bearing journal that encircles the pylon, characterized by the fact that the bearing journal of the lower support is designed to be divided and the support frame has an open longitudinal side through which the support frame with divided bearing journal can slide radially on the pylon.
Preferred embodiments of the invention are described herein.
The turntable is characterized by the fact that the bearing journal of the lower support is divisible, and the support frame of the turntable has an open longitudinal side through which the support frame with divided bearing journal can be slid radially to the pylon. According to the invention, it is therefore not necessary to position the turntable from above and longitudinally in line with the platform. Rather, the turntable is to be positioned transversely, that is, horizontally above the vertical pylon. This allows recessing of the support frame on the sleeve surface side, which recess is at least as large as the profile of the pylon. The narrow width of the opening of the support frame on its longitudinal side is at least the size of the diameter of the pylon. The turntable needs to be raised only high enough to permit it to be slid over the upper support and suspended there.
In a further development of the invention, the support frame consists of two facing side pedestals, connected along one longitudinal side by means of joined cross-braces, and unconnected along a second side, opposite the first side. The unconnected side forms the top-side recess through which the support frame can be lifted onto the pylon from the side. The support frame is thus a framework structure, not a cylindrical sleeve. The side longitudinal braces or side pillars can be designed in various ways. According to one embodiment of the invention they have a rectangular section. The framework-type cross-bracing on one longitudinal side considerably increases the resistance to torsion by the support frame.
At one end, which forms the upper end of the crane when assembled, the two side pillars can be connected preferably by a common head piece, on which deflection sheaves for deflecting a cable of the crane can be positioned. On the opposite end, which, when the crane is assembled, forms the lower end of the support frame, the two side pillars are connected by the bearing journal of the lower support. Especially, one half of the divisible bearing journal can be permanently connected to the two pillars. The detachable portion of the bearing journal can be installed on the lower ends of the side pillars.
The bearing journal of the lower support is divided approximately in half, so that when the removable half is removed the bearing journal segment remaining on the support frame can be slid in a radial direction along the pylon. Advantageously the division plane of the bearing journal is perpendicular to the longitudinal center plane of the turntable, which is defined on the one hand by the longitudinal axis of the pylon and on the other hand by the crane boom connected to the turntable.
Theoretically the bearing journal can be divided into a number of segments. According to one advantageous embodiment of the invention, the bearing journal is constructed in two parts. One half of the bearing journal is constructed in one piece integrated with the support frame. The other half of the bearing journal can have front flange plates that can be bolted to the side pillars of the support frame.
In a further development of the invention, the open longitudinal side of the support frame is positioned on the back of the turntable; that is, the support frame side facing the crane boom is open. The detachable half of the bearing journal of the lower support is accordingly the roller-race half that faces the crane boom. The front side, i.e. the boom side of the bearing journal, is connected permanently and non-detachably to the turntable. This prevents the front section from falling out when the flange connection is opened or breaks. The operator""s cabin, which preferably is connected to the front section of the support ring, is also protected from falling out. This considerably increases safety.
The upper support of the turntable is appropriately constructed as a radial support and an axial support. The lower support can be constructed as a purely radial support.
In contrast to the lower support, the upper support need not be divisible, it can be in one piece. Specifically, the upper support is designed in such manner that it can be installed from the upper end of the pylon on the upper support or on a support piece on the upper end of the pylon. This can considerably facilitate the installation of the turntable on the pylon. Initially the turntable is positioned transversely to the pylon and suspended by its upper end or its upper support on the upper end section of the pylon. Then the lower section of the turntable with its lower support can be swiveled transversely onto the pylon.
To simplify the positioning of the turntable on the pylon in the area of the lower bearing journal, the lower support can have a number of support shoes connected detachably to the bearing journal, so that they can be removed from the bearing journal for the erection of the turntable. Specifically, the support shoes can rest on the inner perimeter surface of the bearing journal and can be connected to said bearing journal in such manner that they can be positioned axially to, that is, parallel to, the longitudinal direction of the pylon between the bearing journal and the pylon, in such manner that they can positioned or removed from the bearing journal. The fact that the support shoes can be mounted parallel to the longitudinal axis of the pylon allows the support shoes to be positioned even subsequently, that is, when the bearing journal is already on the pylon, between the internal perimeter surface of the bearing journal and the external perimeter surface of the pylon. To permit this, provision can theoretically be made for the support shoes to grasp the bearing journal only from the front. Preferably, however, the support shoes have a back that rests flat on the internal perimeter surface of the bearing journal, and flange bridges standing away from the back at right ankles, with which the support shoes grip the bearing journal on both sides. To permit such axial installation, the flange bridges on one axial side can be detachable from the support shoes. The two-sided gripping of the bearing journal permits a non-tipping, solid attachment of the support shoes. Accordingly, after the flange bridge is removed, the support shoes can be pushed to one side axially between the bearing journal and the pylon.
Rotating gear drives for rotating the turntable on the pylon are appropriately mounted on the support frame. Specifically, they can be positioned on that portion of the lower bearing journal that is permanently connected to the support frame side pillars.